150-million-year-old vomit found in Utah offers ‘rare glimpse’ of prehistoric ecosystems

An artist’s drawing of Puffin trying to chase a frog floating on the surface of a pond while another head replenishes part of a recent meal of frogs and salamanders. Puffins are the suspected predator of a 150-million-year-old burrower discovered in southeastern Utah. (Brian Eng through the Utah State Parks Department)

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VERNAL – A fossil recently discovered in southeastern Utah appears to show what kind of predators fed in the age of the dinosaurs, and when the area wasn’t completely desert it is now.

Paleontologists in Utah have discovered a pile of amphibian bones that they say looked like they had been swallowed by some predator. This prehistoric vomit is believed to be 150 million years old, according to paleontologists with the Utah Geological Survey, the Utah Department of State Parks, and the Flying Heritage & Combat Armor Museum in Washington.

Their findings are: They were published last month in the journal Palaios.

“This fossil gives us a rare glimpse into animal interactions in ancient ecosystems,” John Foster, curator of the Utah State Field House Museum of Natural History and one of the study’s co-authors, said in a statement Tuesday.

The team discovered the fossil while searching for Morrison Formation, a popular fossil site known for late Jurassic fossils, which range from about 148 million years ago to 155 million years ago. It is famous for its dinosaur bones, but it is also the place where scientists have found all kinds of other animals, such as fish, salamanders, and frogs.

The formation portion in southeastern Utah is mainly characterized by prehistoric plants such as ginkgo, ferns, and conifers. However, paleontologists have also found amphibians and puffins there. These discoveries are the reason they believe the area was once home to a small pond or lake.

But during a recent study, the team discovered an oddly arranged fossil. It was a collection of bones containing “items” from at least one small frog or tadpole and would be “the smallest salamander specimen reported from the formation,” the researchers wrote in the study. Some of these bones were only 0.12 inches long, one of the smallest groups of bones in the formation.

They added that the chemical composition and skeletal structure of the pit indicated regurgitation, a fossilized form of vomiting. The team notes that this is the first discovery of its kind in the Morrison Formation and also in Jurassic North America.

What remains unclear 150 million years later is what killed the species within the crust. Foster notes that previous research at the time had placed puffins in the area, which he considers to be the “current best match” for the predator behind the fossil. Scientists have discovered fish, salamanders, and frog species in the Morrison Formation for more than a century.

“While we can’t rule out other predators, puffins are currently the suspect, so to speak,” he said, explaining that fish – and other animals – sometimes vomit their last meals when being chased or want to distract a predator.

“Today we still have three animals that interact in a way that is also known between those animals – prey eaten by predators and predators that might be chased by other predators,” he added. “That in itself shows how similar some ancient ecosystems are to places on Earth today.”

This discovery is the team’s latest in the area. Two of the study’s three co-authors are also helping to discover a 151-million-year-old aquatic insect, which led to the publication of a research paper in 2020.

Paleontologist James Kirkland, who co-authored both studies, said the paleontologists plan to continue searching the site where prehistoric vomit was discovered to see if they can find more evidence of the area’s past ecosystem.

“I was very excited to have found this site because plants in the High Jurassic are very rare,” he said in a statement. “Now we need to carefully dissect the site looking for more little wonders among the foliage.”


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Carter Williams is an award-winning reporter who covers general news, outdoor activities, history and sports for KSL.com. Previously he worked at Deseret News. It is planted in Utah via Rochester, New York.

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